Percentage of observations where the VFR minimums for ceiling and visibility are met: visibility of 5 mi or more and a ceiling of 3,000 ft or more. Only observations between sunrise and sunset are taken into account.
Marginal VFR conditions (%)
Month
Average
2024
2023
2022
2021
2020
January
90.4
92
90
87
96
98
February
88.4
94
87
94
99
90
March
90.4
89
92
96
85
90
April
94.5
92
99
93
84
May
97.8
97
96
97
100
June
96.2
85
100
100
100
July
93.8
90
98
93
97
August
88.9
79
94
78
98
September
91.5
87
89
91
90
October
84.4
75
89
86
87
November
84.7
90
79
93
84
December
82.6
93
78
80
87
Average
91.1
91.3
88.1
92.9
90.3
92.2
Marginal VFR conditions or better during daylight period
Percentage of observations where the MVFR minimums for ceiling and visibility are met: visibility of 3⅛ mi or more and a ceiling of 1,000 ft or more. Only observations between sunrise and sunset are taken into account.
Maximum temperatures (°C)
Month
Average
2024
2023
2022
2021
2020
January
-19.2
-21
-15
-20
-14
-25
February
-16.5
-12
-17
-17
-21
-19
March
-8.7
-5
-7
-5
-10
-10
April
1.6
-4
3
1
1
May
13.9
14
13
13
15
June
21.2
19
22
21
22
July
22.3
23
21
21
20
August
17.3
20
17
16
21
September
11.1
10
12
10
11
October
0.3
-1
-1
1
-1
November
-12.7
-6
-11
-16
-13
December
-15.2
-16
-16
-18
-12
Average
0.0
-13.0
1.8
2.1
0.3
0.9
Average highest temperature per day
The maximum temperature is typically observed some hours after noon.